There is a serious deficiency in delivering basic immunization services to U.S. children under two years of age. The hypothesis of this research proposal is that under-immunization of U.S. children is determined by the interaction of the health care system and the knowledge and psychosocial characteristics of parents. In Norfolk, Virginia, there is a CDC-funded intervention project to increase the number of children under two years of age with up-to-date immunizations. The dissertation research proposed in this submission will be nested within, and will contribute to, the large intervention study. The specific aims of the proposed research project are to assess barriers to immunizing preschool children from the parent perspective, and to examine psychosocial and health care utilization factors in relation to immunization coverage of children under two years of age. A baseline survey to assess immunization coverage, demographic characteristics, usual sources of health care and perceived barriers to utilization of immunization services will be conducted in Norfolk and Portsmouth, Virginia in March, 1993. This survey will involve 400 to 450 children aged 12-30 months of age in each city; households will be selected for inclusion based on a multi-stage cluster sampling plan. Approximately 200 mothers in the baseline survey will be included in this nested study. Criteria for inclusion in this subset will be residence in Norfolk and having a child 12-30 months of age. Psychosocial factors to be examined in this subset include: knowledge about immunization schedule, vaccine availability, vaccine preventable disease, and health services that provide the vaccine; attitudes and beliefs regarding severity and infectivity of vaccine- preventable diseases and the safety and efficacy of vaccines. This grant would provide support for the analysis and writing phase of the proposed research on causes of under-immunization of young children.